Disclaimer: Not a defense of BD.
I think you can test the game without compiling. I've only messed around with Ren'Py casually, but it has a mode that lets you play through and debug, so the testing may have been done there.
What's wild is that a compilation error has taken two weeks to sort. I'm calling BS on that if I'm living in a fantasy world where the content and issue actually exist. In reality, there is no compilation error because there is no content to compile.
Yes, he does his "testing" within the renpy dev environment by reviewing the dialog and imagery. He doesn't compile first and then do alpha testing, etc. Someone who operates like him is going to be backwards when it comes to common sense shit like that. But he lost passion for this and it's become a chore that he's stuck with because of how much freaking money it yields to do little to nothing. Add the tendency to put off stuff until the last minute and you end up with what you have. A bunch of scrambling, failure and then lies to cover those failures up. People who hate him though won't accept the whole truth of the situation, only the parts that confirm their biases. Anyone who makes a practice of doing things like that is going to fail hard.
So to recap, he's been putting off work until the last minute, trying to bust it out quickly, failing, then scrambling to get it done ASAP without even tasting the stuff properly before release. He literally compiles as the very last step and, barring any errors prohibiting completion of the package, and then immediately uploads the file. If he doesn't change that flow, I guarantee that it will be impossible to ever make it better. Odds are he's going to keep on doing what he's doing until enough support goes away. I mean what else is he cut out to do? Flip burgers? Stock shelves? I bet that any proper jobs he has had have been a complete disaster. At least knowing he has limited options keeps the glimmer of hope alive that this story will be finished. That and sunken cost has possibly thousands of people jammed up and refusing to cut their losses just yet.